Systems and methods are disclosed for more efficiently (and/or securely) using secrets (e.g., cryptographic keys and/or the like) to protect digital content or other data (e.g., digital media content, other cryptographic keys, and/or the like). For example, in one embodiment a system is disclosed in which a client application facilitates the establishment of a secure channel with a server using an application programming interface with a secure processing environment (e.g., a secure processor running on the client system). The client application receives data over the secure channel, encrypted using keying material determined during the establishment of the channel. The client application invokes the secure processing environment to decrypt the encrypted data, which data includes data further encrypted with the aforementioned keying material (or additional keying material derived therefrom or otherwise related thereto). The client application further invokes the secure processing environment to decrypt this additional encrypted data, which the secure processing environment does, using keying material determined during the establishment of the channel with the server (or information derived therefrom or related thereto). In some embodiments the secure processing environment passes the decrypted data back to the application. In other embodiments, the secure processing environment uses the decrypted data to perform further processing, the results of which are returned to the application. For example, in one embodiment, the secure processing environment uses keying material determined during the establishment of a secure channel to decrypt a content decryption key which it then uses to decrypt media content, which is then returned to the client application.